1. Field of the Invention
The invention relates to a sheet treating apparatus of which the installation area and cost can be reduced and an image forming apparatus having the same. Particularly the invention relates to a construction for delivering sheets to a sheet stacking portion. The invention also relates to the sheet aligning operation performed when a sheet is treated.
2. Related Background Art
Some image forming apparatuses such as copying machines, printers and facsimile apparatuses have a sheet treating apparatus adapted to successively introduce sheets after images have been formed thereon into the apparatus, and effect the stitching treatment on these sheets, in order to mitigate the time and labor required for the stitching treatment, for example, for sheets such as copy paper after images have been formed thereon.
As such a sheet treating apparatus, there is known one a type which is provided on a side of the sheet delivery port of the main body of an image forming apparatus, and successively aligns sheets supplied from the delivery port after being on the main body side of the image forming apparatus, and thereafter effects the stitching treatment on these sheets and delivers them.
Now, in such a conventional image forming apparatus, for example, in order to enable sheets subjected to image formation (printing) on the main body side of the image forming apparatus to be stitched in the order of pages, a switchback mechanism for inverting the sheets to the sheet treating apparatus side is provided so as to deliver and stack the sheets in the order of pages.
However, when the switchback mechanism is thus provided, there has been the inconvenience that the spacing between the sheets must be widened for switchback. Also, the sheet treating apparatus is provided on a side of the sheet delivery port of the main body of the image forming apparatus, and this also has led to the inconvenience that not only the installation area of the entire apparatus is increased, but also the cost thereof becomes high.
Also, some of staple stackers serving both to stack sheets not subjected to treatment and to stack sheets subjected to treatment such as stapling have two sheet transport paths, and when the two sheet transport paths are thus provided, there has been the inconvenience that not only the apparatus becomes bulky, but also the cost thereof becomes high.
Also, in such a conventional sheet treating apparatus, it is necessary, for example, to align sheets before effecting the stitching treatment on the sheets subjected to image formation (printing) on the main body side of the image forming apparatus and therefore, provision is made of a dedicated aligning and stacking portion for stacking the aligned sheets thereon. However, when the dedicated aligning and stacking portion is thus provided, there has been the inconvenience that not only the apparatus becomes bulky, but also the cost thereof becomes high.